Perpendicular magnetic recording head

ABSTRACT

A perpendicular magnetic recording (PMR) head comprises a PMR pole having at least one side, a bottom, and a top wider than the bottom, a first portion of the at least one side being substantially vertical, a second portion of the at least one side being nonvertical, the top portion having a width not greater than one hundred fifty nanometers. The PRM head further comprises a nonmagnetic layer surrounding the bottom and the at least one side of the PMR pole, an intermediate layer substantially surrounding at least the second portion of the at least one side of the PMR pole, and a hard mask layer adjacent to the first portion of the at least one side of the PMR pole.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/121,624, filed on May 15, 2008, which is hereby incorporated byreference in its entirety.

BACKGROUND

FIG. 1 is a flow chart depicting a conventional method 10 forfabricating a conventional perpendicular magnetic recording (PMR)transducer. For simplicity, some steps are omitted. The conventionalmethod 10 is used for providing a PMR pole. An intermediate layer,chemical mechanical planarization (CMP) stop layer and hard mask layerare provided, via step 12. The intermediate layer is typically aluminumoxide. The CMP stop layer may include Ru, while the hard mask layer mayinclude NiCr. A photoresist mask is provided on the hard mask layer, viastep 14. The photoresist mask includes an aperture above the portion ofthe intermediate layer in which the PMR pole is to be formed. Aconventional aperture is formed in the hard mask layer, via step 16.Typically, this is accomplished through using a conventional ion mill.Step 16 also includes forming a conventional aperture in the CMP stoplayer. Thus, through ion milling in step 16, the pattern of thephotoresist mask is transferred to both the hard mask and the CMP stoplayer in a conventional manner.

Using the hard mask and photoresist mask, a trench is formed in thealuminum oxide layer, via step 18. Step 18 is typically performed usingan alumina reactive ion etch (RIE). The top of the trench 66 is desiredto be wider than the trench bottom. In addition, the trench may extendthrough the aluminum oxide intermediate layer. As a result, the PMR poleformed therein will have its top surface wider than its bottom.Consequently, the sidewalls of the PMR pole will have a reverse angle.The conventional PMR pole materials are deposited, via step 20. A CMP isthen performed, via step 22. The stop layer provided in step 12 is usedto terminate the CMP. Thus, the conventional PMR pole is provided.Subsequent structures, such as a write gap and shields, may then beprovided.

Although the conventional method 10 may provide the conventional PMRtransducer, there may be drawbacks. Use of the photoresist mask and hardmask may result in relatively large variations in the critical dimensionof the conventional PMR pole. The critical dimension corresponds to thetrack width of the conventional PMR pole. Such variations in track widthmay adversely affect fabrication and performance. In addition, theconventional PMR pole may be relatively large in size. Usingconventional photolithography, the critical diameter of the aperturesformed in step 16, and thus the trench provided in step 18, is typicallygreater than 150 nm. Consequently, without more, the conventional PMRpoles formed using the conventional method 10 may not be usable in highdensity magnetic recording technology.

Accordingly, what is needed is an improved method for fabricating a PMRtransducer.

SUMMARY

A method and system for providing a PMR pole in a magnetic recordingtransducer are disclosed. The magnetic recording transducer includes anintermediate layer. The method and system include providing a maskincluding a line on the intermediate layer. The method further includeproviding a hard mask layer on the mask and removing the line. Thus, anaperture in a hard mask corresponding to the line is provided. Themethod and system also include forming a trench in the intermediatelayer under the aperture. The trench has a bottom and a top wider thanthe bottom. The method further includes providing a PMR pole, at least aportion of which resides in the trench.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a flow chart depicting a conventional method for fabricating aPMR head.

FIG. 2 is a flow chart depicting an exemplary embodiment of a method forfabricating a PMR transducer.

FIG. 3 is a flow chart depicting another embodiment of a method forfabricating a PMR transducer.

FIGS. 4-13 are diagrams depicting an exemplary embodiment of aperpendicular magnetic recording transducer during fabrication.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 2 is a flow chart depicting an exemplary embodiment of a method 100for fabricating a PMR pole for a PMR transducer. For simplicity, somesteps may be omitted. The PMR transducer being fabricated may be part ofa merged head that also includes a read head (not shown) and resides ona slider (not shown). The method 100 also may commence after formationof other portions of the PMR transducer. The method 100 is alsodescribed in the context of providing a single PMR pole in a singlemagnetic recording transducer. However, the method 100 may be used tofabricate multiple transducers at substantially the same time. Themethod 100 and system are also described in the context of particularlayers, such as a BARC layer. However, in some embodiments, such layersmay include multiple sub-layers.

In one embodiment, the method 100 commences after formation of theintermediate layer(s) in which the PMR pole is to reside. In oneembodiment, the intermediate layer is an insulator such as alumina. Theintermediate layer may reside on an underlayer. Further, in oneembodiment, the underlayer layer may be an etch stop layer. A mask isprovided on the intermediate layer, via step 102. The mask includes aline that corresponds to the location of the PMR pole. In oneembodiment, the mask is a photoresist mask and may be formed usingphotolithographic techniques. For example, a BARC might be used in orderto improve formation of the line. The BARC reduces reflections informing a photoresist mask on the BARC layer. In such an embodiment,formation of the mask may further include removal of any BARC exposed bythe mask. A hard mask layer is provided on the mask, via step 104. Forexample, step 104 may include deposition of a material such as NiCr, Cr,and/or Ru.

The line in the mask is removed, via step 106. In one embodiment, step106 may include removal of corresponding structures, such as any BARCresiding beneath the line. In one embodiment, step 106 includesperforming a planarization, such as a CMP, and a lift-off of anyremaining photoresist. The hard mask is thus formed. In particular,removal of the line forms an aperture corresponding to the line. Theaperture in the hard mask resides in substantially the position occupiedby the line.

A trench is formed in the intermediate layer under the aperture, viastep 108. The trench has a bottom and a top wider than the bottom.Consequently, the trench formed is appropriate for a PMR pole. In oneembodiment, the trench extends through the intermediate layer. However,in another embodiment, the trench might extend only partially throughthe intermediate layer. In one embodiment, step 108 includes performinga RIE.

A PMR pole is provided, via step 110. At least a portion of the PMR poleresides in the trench. In one embodiment, only part of the PMR poleresides within the trench in the intermediate layer. Thus, the top ofthe PMR pole would be above the top of intermediate layer. In analternate embodiment, the entire PMR pole resides within the trench.Formation of the PMR pole in step 110 may include providing anonmagnetic layer in the trench. Such a nonmagnetic layer might be usedto adjust the critical dimension, and thus the track width, of the PMRpole. Thus, the PMR pole would reside on such a nonmagnetic layer. Inone embodiment, the nonmagnetic layer may be provided using atomic layerdeposition (ALD). As part of step 110 a planarization stop layer mightalso be provided. In one embodiment, the planarization stop layer isprovided on the nonmagnetic layer. The planarization stop layer may be aCMP stop layer. In one such embodiment, the planarization stop layerincludes Ru. A seed layer for the PMR pole may also be provided on theplanarization stop layer. In another embodiment, the planarization stoplayer may also function as a seed layer. The layer(s) for the PMR polemay then be blanket deposited. A planarization, such as a CMP, may beperformed. In addition, the geometry of the PMR pole might be furtheradjusted using an ion beam etch. Thus, the PMR pole may be formed.Although described above as part of formation of the PMR pole, at leastsome of the steps of providing the nonmagnetic layer, the planarizationstop layer and/or the seed layer may be considered separate fromproviding the PMR pole.

Using the method 100, at least part of a PMR transducer may be formed.The method 100 utilizes the photoresist line to provide the aperture inthe hard mask. In one embodiment, the line in the mask may have acritical dimension, or width, that is not larger than one hundred-fiftynanometers. The critical dimension of the line might also be not morethan one hundred nanometers. As a result, the critical dimension for thePMR pole may be not more than one hundred-fifty nanometers in oneembodiment. In another embodiment, the critical dimension might be notmore than on hundred nanometers. The PMR transducer formed may thus beused at higher densities. For example, the PMR transducer formed mightbe usable in 400 Gb/in² or higher density transducers. Using the method100, therefore, a PMR transducer usable at higher densities may befabricated.

FIG. 3 is a flow chart depicting another exemplary embodiment of amethod 150 for fabricating a PMR transducer. For simplicity, some stepsmay be omitted. FIGS. 4-13 are diagrams depicting an exemplaryembodiment of a PMR transducer 200 as viewed from the ABS duringfabrication. For clarity, FIGS. 4-13 are not to scale. Referring toFIGS. 3-13, the method 150 is described in the context of the PMRtransducer 200. However, the method 150 may be used to form anotherdevice (not shown). The PMR transducer 200 being fabricated may be partof a merged head that also includes a read head (not shown) and resideson a slider (not shown). The method 150 also may commence afterformation of other portions of the PMR transducer 200. The method 150 isalso described in the context of providing a single PMR transducer.However, the method 150 may be used to fabricate multiple transducers atsubstantially the same time. The method 150 and device 200 are alsodescribed in the context of particular layers, such as a bottomantireflective coating (BARC) layer. However, in some embodiments, suchlayers may include multiple sublayers.

The method 150 commences after an intermediate layer is provided. Theintermediate layer may be an alumina layer. A BARC is provided on theintermediate layer, via step 152. A photoresist mask is provided on theBARC, via step 154. The photoresist mask includes a line thatcorresponds to the location of the PMR pole. FIG. 4 depicts a portion ofthe PMR transducer 200 after step 154 is performed. In the embodimentshown, an underlayer 202 that may also functions as an etch stop layer202, is shown. In addition, an intermediate layer 204 is also depicted.The PMR transducer 200 also includes a BARC 206 and a mask 208. In theembodiment shown, the mask 208 is shown as consisting of a line.However, in another embodiment, the mask 208 may include other features.

The pattern of the mask 208 is transferred to the BARC 206, via step156. FIG. 5 depicts the PMR transducer 200 after step 156 is performed.Thus, the BARC 206′ resides only under the line 208. A hard mask layeris provided on the PMR transducer 200, via step 158. Step 158 mayinclude deposition of a material such as NiCr, Cr, and/or Ru. FIG. 6depicts the PMR transducer 200 after step 158 is performed. Thus, a hardmask layer 210 has been provided.

A planarization, such as a CMP, is performed to expose the line of themask 208, via step 160. FIG. 7 depicts the PMR transducer after step 160has been performed. Thus, a hard mask 210′ has been formed from the hardmask layer 210. The hard mask 210′ includes an aperture 212. Inaddition, a remaining portion 208′ of the line of the mask is shown.Because of the CMP, the top surface of the PMR transducer 210 issubstantially flat. Thus, the remaining portion 208′ of the line and thehard mask 210′ have top surfaces at substantially the same level. Theaperture 212 corresponds to the line of the mask 208. As a result, thelocation and size of the aperture 212 match that of the line.

A lift-off is performed, via step 162. As a result, the remainingportion 208′ of the line is removed. In addition, the remaining portion206′ of the BARC that was under the line is removed, via step 164. FIG.8 depicts the PMR transducer 200 after step 164 is completed. Thus, theaperture 212 in the hard mask 210′ exposes the underlying intermediatelayer 204.

A RIE is performed to form a trench in the intermediate layer 204, viastep 166. In one embodiment, the RIE is performed utilizing aCl-containing gas. FIG. 9 depicts the PMR transducer after step 166 isperformed. Thus, a trench 213 has been formed in the intermediate layer204′. For clarity, the aperture 212 is no longer labeled. However, thetrench 213 is formed under the aperture 212. The trench 213 has a bottomand a top wider than the bottom.

The PMR pole is then formed. This may occupy a number of steps. In oneembodiment, a nonmagnetic layer is provided in the trench 213, via step168. At least a portion of the nonmagnetic layer resides in the trench213. In one embodiment, step 168 may be performed using ALD. However, inanother embodiment, another method for providing the nonmagnetic layermay be used. Alternatively, step 168 might be omitted. Because it ismagnetically separate from the pole being formed, the nonmagnetic layermay be used to reduce the critical diameter of the pole being formed.Stated differently, the nonmagnetic layer may be considered to make thetrench 213 less wide and, in one embodiment, shallower. Thus, thethickness of the nonmagnetic layer may be used to tune the width of thePMR pole being formed. In particular, the width the PMR pole beingformed may be reduced by twice the thickness of the nonmagnetic layer.For example, in one embodiment, the nonmagnetic layer may be at leastfifty and not more than four hundred Angstroms. Consequently, use of anonmagnetic layer in such an embodiment allows the width of the PMR polebeing formed to be reduced by one hundred to eight hundred Angstroms.

A planarization stop layer is provided on the nonmagnetic layer, viastep 170. In one embodiment, the planarization stop layer is a CMP stoplayer and may include materials such as Ru. A seed layer may also beprovided on the CMP stop layer, via step 172. Such a seed layer may benonmagnetic or magnetic. If magnetic, the seed layer may be magneticallyindistinct from the PMR pole. Thus, the seed layer may be consideredpart of the PMR pole. In another embodiment, the seed layer may benonmagnetic. In such an embodiment, the seed layer would be magneticallydistinct from the PMR pole. In one embodiment, the seed layer and theplanarization stop layer may function as a single layer or be mergedinto a single layer. FIG. 10 depicts the PMR transducer 200 after step172 is performed. Thus, a nonmagnetic layer 214, a CMP stop layer 216,and a seed layer 218 are all shown. A portion of each of the nonmagneticlayer 214, the CMP stop layer 216, and the seed layer 218 resides in thetrench 213. However, another portion of each of the nonmagnetic layer214, the CMP stop layer 216, and the seed layer 218 also resides on andnext to the hard mask 210′. Thus, a portion of the nonmagnetic layer 214is above the top of the intermediate layer 204′.

A PMR pole layer(s) may be provided, via step 174. Step 174 may includeplating the PMR pole layer(s). In one embodiment, a single layer isused. However, in another embodiment, multiple layers might be used forthe PMR pole. Consequently, multiple layers might be deposited in step174. In the embodiment described, the PMR pole layer(s) are blanketdeposited. However, in another embodiment, masking might be used. In oneembodiment, the PMR pole layer is plated on the planarization stop layer216. In an embodiment in which a separate seed layer is used, the PMRpole layer may also be plated on the seed layer 218 and, if used, thenonmagnetic layer 214.

FIG. 11 depicts the PMR transducer 200 after step 174 is performed.Thus, the PMR pole layer 220 resides in the trench 213. However, anotherportion of the PMR pole layer 220 also resides on and next to the hardmask 210′. Thus, a portion of the PMR pole layer 220 is above the top ofthe intermediate layer 204′. A CMP, or other planarization selected, isperformed, via step 176. The CMP planarization may terminate when atleast a portion of the planarization stop layer 216 remains. Inaddition, an ion beam etch might also be performed in step 176 tofurther configure the geometry of the PMR pole.

FIG. 12 depicts the PMR transducer 200 after step 176 has beenperformed. Consequently, the PMR pole 220′ has been formed from the PMRpole layer(s) 220. In addition, a portion of the seed layer 218 and, insome embodiments, a portion of the CMP stop layer 216 have been removed.Consequently, only portions of the seed layer 214″, portions of CMP stoplayer 216′, and nonmagnetic layer 214 remain after step 176 isperformed. In the embodiment shown, only a portion of the PMR pole 220′resides within the trench 213. This portion of the PMR pole 220′ has atop wider than the bottom. Stated differently, there is a negative angle(as measured from vertical) for these portions of the sidewalls of thePMR pole 220′. A remaining portion of the PMR pole 220′ is next to thehard mask layer 210′, nonmagnetic layer 220, and remaining planarizationstop layer 222′. The sidewalls for this portion of the PMR pole 220′ ares substantially vertical.

Fabrication of the PMR transducer 200 might then be completed. Forexample, a write gap, a shield, and other structures might be provided.FIG. 13 depicts the PMR transducer 200 after such structure areprovided. Thus, the write gap 222 and top shield 224 are shown. In oneembodiment, the write gap 228 may be an insulator, such as aluminumoxide. In another embodiment, other material(s) may be used.

Using the method 150, at least part of the PMR transducer 200 may beformed. The method 150 utilizes the photoresist line of the mask 208 toprovide the aperture 212 in the hard mask 210′. In one embodiment, theline in the mask 208′ may have a critical dimension, or width, that isnot larger than one hundred-fifty nanometers. The critical dimension ofthe line 208 might also be not more than one hundred nanometers. As aresult, the critical dimension for the PMR pole 220′ may be not morethan one hundred-fifty nanometers in one embodiment. In anotherembodiment, the critical dimension might be not more than one hundrednanometers. The PMR transducer 200 may thus be used at higher densities.For example, the PMR transducer 200 might be usable in 400 Gb/in² orhigher density transducers. Using the method 150, therefore, a PMRtransducer 200 usable at higher densities may be fabricated.

1. A perpendicular magnetic recording (PMR) head comprising: a PMR polehaving at least one side, a bottom, and a top wider than the bottom, afirst portion of the at least one side being substantially vertical, asecond portion of the at least one side being nonvertical, the topportion having a width not greater than one hundred fifty nanometers; anonmagnetic layer surrounding the bottom and the at least one side ofthe PMR pole; an intermediate layer substantially surrounding at leastthe second portion of the at least one side of the PMR pole; and a hardmask layer adjacent to the first portion of the at least one side of thePMR pole.
 2. The PMR head of claim 1 further wherein the width is notmore than one hundred nanometers.
 3. The PMR head of claim 1 furthercomprising: a planarization stop layer residing between the nonmagneticlayer and the PMR pole.
 4. The PMR head of claim 3 further comprising: aseed layer residing between the planarization stop layer and the PMRpole.
 5. A disk drive including a perpendicular magnetic recording (PMR)head comprising: a PMR pole having at least one side, a bottom, and atop wider than the bottom, a first portion of the at least one sidebeing substantially vertical, a second portion of the at least one sidebeing nonvertical, the top portion having a width not greater than onehundred fifty nanometers; a nonmagnetic layer surrounding the bottom andthe at least one side of the PMR pole; an intermediate layersubstantially surrounding at least the second portion of the at leastone side of the PMR pole; and a hard mask layer adjacent to the firstportion of the at least one side of the PMR pole.
 6. The disk drive ofclaim 5 further wherein the width is not more than one hundrednanometers.
 7. The disk drive of claim 5 further comprising: aplanarization stop layer residing between the nonmagnetic layer and thePMR pole.
 8. The disk drive of claim 7 further comprising: a seed layerresiding between the planarization stop layer and the PMR pole.